The invention relates to a joining device for joining together at right angles two furniture parts, comprising a cylindrical dowel casing adapted to be inserted into a bore at the side face of one furniture part. The dowel casing has an aperture into which a screw screwed into the other furniture part is eccentrically insertable. The screw is fastenable to the dowel casing by means of a holding member pivotally mounted in the dowel casing. The dowel casing at its circumference is provided with clamping ribs.